1 / 20

Continuous Run in May 2013

Continuous Run in May 2013. 2013.05.29 K.Kubo. Accelerator Test Facility (ATF) at KEK. Focal Point. Extraction Line. IP; ~40 nm beam. Final Focus Test Line. ATF Damping Ring (140 m). Photo-cathode RF Gun. ATF Linac (1.3 GeV). Strategy of the 2 weeks.

emi-lynn
Download Presentation

Continuous Run in May 2013

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Continuous Run in May 2013 2013.05.29 K.Kubo

  2. Accelerator Test Facility (ATF) at KEK Focal Point Extraction Line IP; ~40 nm beam Final Focus Test Line ATF Damping Ring (140 m) Photo-cathode RF Gun ATF Linac (1.3 GeV)

  3. Strategy of the 2 weeks Achieving (confirming) small beam size at low intensity is the top priority • Optics 10x1 • Try all knobs Other important issues to be studied • Wakefield study • Effect of bellows hields. • Studies using bellows on mover • Emittancein extraction line • More reliable IP beam size measurement

  4. Procedure Scenario of 2013 May continuous operation (by T. Okugi in meeting 2013 May 10) 1) DR tuning and optimize the frequency. ‐ tuned on the DR orbit FB?? 2) EXT tuning ‐ orbit, dispersion and coupling tuning. ‐ emittance measurement ( if we can not use OTR3X, we measure the emittance OTR0‐2X and MW3X). ‐ matching to FF. 3) IP beam size measurement with MWIP ‐ IP horizontal dispersion correction by changing QF1FF. ‐ IP horizontal waist optimization by changing AX knob. ‐ IP vertical waist optimization by changing QD0FF. ‐ BBA of sextupoles and tuned on the sextupoles. 4) Startup the IP‐BSM ‐ Linear knob optimization by 2‐8 deg. mode ‐ Linear knob optimization by 30 deg. mode ‐ Beam orbit was set and optimize the mover bellows to be small intensity dependence of IP beam size. ‐ tuned on the FF orbit FB. ‐ Linear knob optimization by 30 deg. mode again. 5) IP beam size measurement by IP‐BSM 174 deg. mode. ‐ Fringe tilt & pitch optimization ‐ Linear and nonlinear knob tuning

  5. Continuous Run, May 13-24

  6. Bellows shields inserted Shields were inserted for most of bellows in high-beta region in May 2013.

  7. Troubles with bellows shield Found and removed Wed., May 15.

  8. Big daily temperature change in sunny daysMachine was not very stable (DR circumference change) May 21 May 19 May 20 May 24 May 23 May 22 Graphs from Japan Meteorological Agency http://www.data.jma.go.jp/obd/stats/etrn/

  9. Study Shift Study leaders: Okugi, Kuroda, Kubo, White, Marin, Terunuma, Tauchi Sub leaders: A: Young-Im Kim, Janice Nelson B: ShaBai, Shan Liu C: Yves Renier y, JuergenPfingstner, Andrea Jeremie(1st week) D:Neven Blaskovic, Jacqueline Yan, Robert Ainsworth

  10. Emiitance in Extraction Line (multi-OTR monitors) • QS magnets were used for coupling correction. • We had used only QK magnets before. • QSs had been used only for dispersion correction. • Strength oｆ QK magnets significantly reduced. • QS: upstream of EXT line, in dispersive region • QK: Just before beam size measurement. Dispersion free region. • Rotation of OTR monitor Adjusted Vertical emittance ~13 pm at N=6e9 ~10 pm at low intensity Improved

  11. Examples of 174 deg mode fringe scans Beam size ~ 60 and ~ 90 nm Preliminary Preliminary

  12. Intensity dependence Modulation (30 deg.) vs. intensity for different betax* and betay* By T.Okugi Fitting One exception? Almost the same dependence for all cases, a=20nm/1e9 This is slightly larger than in April. Orbit dependence was not systematically studied yet.

  13. Intensity dependence Examples of modulation (30deg) vs. intensity Only this scan shows weak dependence. Others are all similar.

  14. Modulation (30deg) vs. position of on-mover bellowsExample Peak was observed

  15. on-mover wakefield source Dec.2012 Ref. Cav. Ref. Cav. Ref. Cav. Bellows Bellows Bellows Bellows Dec.2012 – April 2012 May 2012 Bellows Shielded Bellows Shielded Bellows

  16. Studies using on-mover wakefield source Modulation (30 deg) vs. position of bellows By T.Okugi • 1 Bellows +2 shielded bellows for movement : 7.9-8.5nm/mm/1e9 • 2 Ref. Cavities +2 bellows for movement: 27-28nm/mm/1e9 • 1 Ref. Cavity +2 bellows for movement: 14-19nm/mm/1e9

  17. Tuning knobs 5 sextupole magnets (on mover), 4 skew-sextupolemagnets

  18. Effect of Non-linear knob Most non-linear knob scans were not effective. Very few exceptions. (Effective just because linear knob scan was not optimized??) Change sextupoles strengths) Could not find effective skew-sextupole knobs scan. (?)

  19. Conclusion of the weeks (1) • Small beam size at low intensity? • Repeatedly achieved < 70nm beam size at low intensity by tuning, and kept hours. • Minimum beam size ~60nm • Could not reduce further • Multi-pole field • We did not see clear effect of the skew-sextupole correctors.

  20. Conclusion of the weeks (2) • Wakefield • Effect of bellows shield was not clear. Intensity dependence did not reduced. • Cannot explain beam size growth 40nm -> 60nm at low intensity (N~1e9) • Similar intensity dependence for different betax* and betay*, suggesting dependence is from wake field, not from multi-pole field. • Emittance in Extraction Line • Improved. Vertical emittance about 10 pm (low intensity) ~ 13 pm (N~6e9), weak intensity dependence. • Coupling correction in upstream part • Tuning of OTR monitor

More Related